Package structure and method for forming the same

ABSTRACT

A package structure and method for forming the same are provided. The package structure includes a substrate and a semiconductor die formed over the substrate. The package structure also includes a package layer covering the semiconductor die and a conductive structure formed in the package layer. The package structure includes a first insulating layer formed on the conductive structure, and the first insulating layer includes monovalent metal oxide. A second insulating layer is formed between the first insulating layer and the package layer. The second insulating layer includes monovalent metal oxide, and a weight ratio of the monovalent metal oxide in the second insulating layer is greater than a weight ratio of the monovalent metal oxide in first insulating layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to the following co-pending a commonlyassigned U.S. patent application Ser. No. 14/970,962, filed on Dec. 16,2015, the entirety of which is incorporated by reference herein.

BACKGROUND

Semiconductor devices are used in a variety of electronic applications,such as personal computers, cell phones, digital cameras, and otherelectronic equipment. Semiconductor devices are typically fabricated bysequentially depositing insulating or dielectric layers, conductivelayers, and semiconductive layers of material over a semiconductorsubstrate, and patterning the various material layers using lithographyto form circuit components and elements thereon. Many integratedcircuits are typically manufactured on a single semiconductor wafer, andindividual dies on the wafer are singulated by sawing between theintegrated circuits along a scribe line. The individual dies aretypically packaged separately, in multi-chip modules, for example, or inother types of packaging.

New packaging technologies, such as package on package (PoP), have begunto be developed, in which a top package with a device die is bonded to abottom package, with another device die. By adopting the new packagingtechnologies, various packages with different or similar functions areintegrated together.

Although existing package structures and methods of fabricating packagestructure have generally been adequate for their intended purpose, theyhave not been entirely satisfactory in all respects.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It shouldbe noted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIGS. 1A-1N show cross-sectional representations of various stages offorming a package structure, in accordance with some embodiments of thedisclosure.

FIG. 1H′ shows a cross-sectional representation of a wet processperformed on the conductive structure, in accordance with someembodiments of the disclosure.

FIG. 2A shows a top-view representation of a conductive structure,before the plasma process or the wet process, in accordance with someembodiments of the disclosure.

FIG. 2B shows a top-view representation of a conductive structure, afterthe plasma process or the wet process, in accordance with someembodiments of the disclosure.

FIG. 3A shows a top-view representation of a conductive structure,before the plasma process or the wet process, in accordance with someembodiments of the disclosure.

FIG. 3B shows a top-view representation of a conductive structure, afterthe plasma process or the wet process, in accordance with someembodiments of the disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the subject matterprovided. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Some variations of the embodiments are described. Throughout the variousviews and illustrative embodiments, like reference numbers are used todesignate like elements. It should be understood that additionaloperations can be provided before, during, and after the method, andsome of the operations described can be replaced or eliminated for otherembodiments of the method.

Embodiments for a package structure and method for forming the same areprovided. FIGS. 1A-1N show cross-sectional representations of variousstages of forming a package structure 100, in accordance with someembodiments of the disclosure. The package structure 100 is applied towafer level package (WLP).

As shown in FIG. 1A, a substrate 102 is provided. The substrate 102 is atemporary support substrate. In some embodiments, the substrate 102 ismade of semiconductor material, ceramic material, polymer material,metal material, another applicable material or combinations thereof. Insome embodiments, the substrate 102 is a glass substrate. In someembodiments, the substrate 102 is a semiconductor substrate, such assilicon wafer.

An adhesive layer 104 is formed on the substrate 102. In someembodiments, the adhesive layer is made of glue or foil. In some otherembodiments, the adhesive layer 104 is made of a photosensitive materialwhich is easily detached from the substrate 102 by light irradiation. Insome embodiments, the adhesive layer 104 is made of a heat-sensitivematerial.

Afterwards, a base layer 106 is formed on the adhesive layer 104. Insome embodiments, the base layer 106 is made of polymer or apolymer-containing layer. The base layer 106 may be apoly-p-phenylenebenzobisthiazole (PBO) layer, a polyimide (PI) layer, asolder resist (SR) layer, an Ajinomoto buildup film (ABF), a die attachfilm (DAF), another applicable material or combinations thereof. In someembodiments, the adhesive layer 104 and the base layer 106 are depositedor laminated over the substrate 102.

Afterwards, a seed layer 108 is formed over the base layer 106 as shownin FIG. 1B, in accordance with some embodiments of the disclosure. Insome embodiments, the seed layer 108 is made of metal material, such ascopper (Cu), titanium (Ti), copper alloy, titanium alloy or combinationsthereof. In some embodiments, the seed layer 108 is formed by adeposition process, such as chemical vapor deposition process (CVD),physical vapor deposition process (PVD), another applicable process orcombinations thereof.

After the seed layer 108 is formed on the base layer 106, a mask layer110 is formed on the seed layer 108, as shown in FIG. 1C, in accordancewith some embodiments of the disclosure. The openings 112 are formed inthe mask layer 110. The seed layer 108 is exposed by the openings 112.The openings 112 are used to define the position of the conductivestructure (formed later, shown in FIG. 1D). In some embodiments, themask layer 110 is made of a photoresist material. The openings 112 areformed by a patterning process. The patterning process includes aphotolithography process and an etching process. Examples of aphotolithography process include soft baking, mask aligning, exposure,post-exposure baking, developing the photoresist, rinsing and drying(e.g., hard baking). The etching process may be a dry etching or a wetetching process.

Afterwards, the conductive structure 114 is formed in the mask layer 110as shown in FIG. 1D, in accordance with some embodiments of thedisclosure. The conductive structure 114 is filled into the openings112. The conductive structure 114 may be made of metal material, such ascopper (Cu), aluminum (Al), tungsten (W), nickel (Ni), alloy thereof orcombinations thereof. The top-view shape of the conductive structure 114may be rectangle, square, circle, or the like. The height of theconductive structure 114 dependents on the thickness of the mask layer110. In some embodiments, the conductive structure 114 is formed by aplating process.

Afterwards, the mask layer 110 is removed, and an etching process isperformed to remove a portion of seed layer 108 as shown in FIG. 1E, inaccordance with some embodiments of the disclosure. During the etchingprocess, the conductive structure 114 is used as a mask. As a result,the conductive structure 114 and the remaining seed layer 108 are incombination referred to as through InFO vias (TIV) 116, which are alsoreferred to as through-vias 116. In some embodiments, the conductivestructure 114 and the seed layer 108 are made of the same material, andtherefore there is no distinguishable interface therebetween.

Afterwards, a semiconductor die 120 is formed over the base layer 106through an adhesive layer 122 as shown in FIG. 1F, in accordance withsome embodiments of the disclosure. The height of the conductivestructure 114 is higher than the height of the semiconductor die 120.The top surface of the conductive structure 114 is higher than the topsurface of the semiconductor die 120.

In some embodiments, the adhesive layer 122 is die attach film (DAF).The semiconductor die 120 includes a semiconductor substrate 124, adielectric layer 126, a conductive pad 128, a passivation layer 130 anda connector 132. The conductive pad 128 is formed in the dielectriclayer 126, and the connector 132 is formed in the passivation layer 130.The connector 132 is electrically connected to the conductive pad 128.

Other device elements may be formed in the semiconductor die 120. Thedevice elements include transistors (e.g., metal oxide semiconductorfield effect transistors (MOSFET), complementary metal oxidesemiconductor (CMOS) transistors, bipolar junction transistors (BJT),high-voltage transistors, high-frequency transistors, p-channel and/or nchannel field effect transistors (PFETs/NFETs), etc.), diodes, and/orother applicable elements. Various processes are performed to formdevice elements, such as deposition, etching, implantation,photolithography, annealing, and/or other applicable processes.

As shown in FIG. 1G, a first insulating layer 136 a is spontaneouslyformed on the conductive structure 114. The first insulating layer 136 asurrounds the conductive structure 114. In other words, the conductivestructure 114 and the seed layer 108 are surrounded by the firstinsulating layer 136 a.

The conductive structure 114 includes a metal material, and the firstinsulating layer 136 a includes a metal element that is the same as thatof the metal material. In some embodiments, the first insulating layer136 a is a native oxide layer. In some embodiments, the conductivestructure 114 includes copper (Cu), and the first insulating layer 136 aincludes cupric oxide and cuprous oxide (CuO and Cu₂O).

It should be noted that the first insulating layer 136 a is formedbetween the conductive structure 114 and a package layer (formed later,such as package layer 140 shown in FIG. 1I). However, delaminationbetween the first insulating layer 136 a and the package layer may occurduring a subsequent process, such as a heating process. For example,during a heating operation, the heat may cause stress, and it may causedelamination of the package layer.

In some embodiments, a plasma process 11 is performed on the conductivestructure 114 and transforms an outer part of the first insulating layerto a second insulating layer 136 b, in accordance with some embodimentsof the disclosure. For example, the second insulating layer 136 b isformed over the conductive structure 114, as shown in FIG. 1H. Comparedwith the surface of the first insulating layer 136 a before performingthe plasma process 11, a roughened surface on the second insulatinglayer 136 b is obtained after the plasma process 11 is performed. Thefirst insulating layer 136 a′ has a first thickness T₁, and the secondinsulating layer 136 b has a second thickness T₂. In some embodiments, aratio (T₁/T₂) of the first thickness T₁ to the second thickness T₂ is ina range from about 1/1 to about 1/0.2.

After the plasma process 11, the insulating layer 136 includes the firstinsulating layer 136 a′ and the second insulating layer 136 b. The firstinsulating layer 136 a′ is closer to the conductive structure 114 thanthe second insulating layer 136 b. In other words, the first insulatinglayer 136 a′ is formed in direct contact with the conductive structure114, and the second insulating layer 136 b is formed in direct contactwith the package layer 14 o (shown in FIG. 1I). The dash line in theinsulating layer 136, as shown in FIG. 1H, is used to schematicallydefine the two layers. In other words, the insulating layer 136 includesmonovalent metal oxide at a first location near an outside surface ofthe insulating layer 136 more than it at a second location near an innersurface which is in contact with the conductive structure 114. Thedescription of “near an outer surface” is in the thickness range of thesecond insulating layer 136 b, and “near an inner surface” is in thethickness in the first insulating layer 136 a′.

In some embodiments, compositions of monovalent metal oxide and divalentmetal oxide in two layers 136 a′, 136 b are different. For example, theweight ratios of monovalent metal oxide and divalent metal oxide aredifferent in the first insulating layer 136 a′ and the second insulatinglayer 136 b. The adhesion may be improved to avoid delamination problemsby forming the second layer 136 b.

The conductive structure 114 includes a metal material, and the firstinsulating layer 136 a′ and the second insulating layer 136 b includethe same metal element as that of the metal material. More specifically,both the first insulating layer 136 a′ and the second insulating layer136 b include monovalent metal oxide and divalent metal oxide, and thesecond insulating layer 136 b includes a higher ratio of monovalentmetal oxide. For example, the conductive structure 114 includes copper(Cu), and the first insulating layer 136 a′ and the second insulatinglayer 136 b include cupric oxide (CuO) and cuprous oxide (Cu₂O).

It should be noted that a weight ratio of the monovalent metal oxide inthe second insulating layer 136 b is greater than a weight ratio of themonovalent metal oxide in the first insulating layer 136 a′. In someembodiments, the conductive structure 114 includes copper (Cu), and aweight ratio of cuprous oxide (Cu₂O) in the second insulating layer 136b is greater than that of cuprous oxide (Cu₂O) in the first insulatinglayer 136 a′. In some embodiments, the weight ratio of cuprous oxide(Cu₂O) in the second insulating layer 136 b is in a range from about 30%to about 60%. In some embodiments, the weight ratio of cuprous oxide(Cu₂O) in the first insulating layer 136 a′ is in a range from about 20%to about 28%. In some embodiments, the weight ratio of cuprous oxide(Cu₂O) in the second insulating layer 136 b is about 1.5 to 3 times ofthat of cuprous oxide (Cu₂O) in the first insulating layer 136 a′.

In some other embodiments, the weight ratio of cuprous oxide (Cu₂O) andcupric oxide (CuO) in the second insulating layer 136 b graduallyincreases from the inner surface to the outer surface of the secondinsulating layer 136 b. The inner surface is the interface between thefirst insulating layer 136 a′ and the second insulating layer 136 b. Theouter surface is the interface between the second insulating layer 136 band the package layer 140. In some embodiments, the weight ratio ofcuprous oxide (Cu₂O) and cupric oxide (CuO) is substantially constant inthe first insulating layer 136 a′.

Furthermore, the surface roughness of the second insulating layer 136 bis greater than that of the first insulating layer 136 a′. The highroughness increases the contact area, and therefore improves adhesionstrength. The adhesion between the conductive structure 114 and thepackage layer 140 is improved by treating the surface of the conductivestructure 114.

In other words, the monovalent metal oxide provides better bondingcharacteristics between the conductive structure 114 and thesubsequently formed package layer 140, comparing with the divalent metaloxide.

In some embodiments, the plasma process 11 includes performing apre-cleaning process and a main plasma process. The pre-cleaning processis configured to clean the surface of the conductive structure 114 andto remove some contaminations. If the contaminations are not removed,they may hinder and decrease the adhesion between the conductivestructure 114 and the package layer 140. The main plasma process isconfigured to alter the components of the first insulating layer 136 a.Therefore, the second insulating layer 136 b formed over the firstinsulating layer 136 a′ is obtained.

In some embodiments, the cleaning process includes using nitrogen (N₂)gas with a flow rate in a range from about 200 sccm to about 600 sccm.In some embodiments, the cleaning process is performed at a pressure ina range from about 20 Pa to about 70 Pa. In some embodiments, thecleaning process is performed for a period of time in a range from about10 seconds to about 70 seconds. When the pre-cleaning process isperformed for a period of time within the above-mentioned range, thecontaminations are removed completely.

In some embodiments, the main plasma process includes using oxygen (O₂)gas with a flow rate in a range from about 100 sccm to about 300 sccm.In addition oxygen (O₂) gas, the main plasma process also includes usingargon (Ar) gas with a flow rate in a range from about 100 sccm to about300 sccm. The argon (Ar) gas is also used to increase surface roughness.In some embodiments, the main plasma process is performed at a pressurein a range from about 20 Pa to about 40 Pa. In some embodiments, themain plasma process is performed for a period of time in a range fromabout 5 seconds to about 50 seconds. When the main plasma process isperformed for a period of time within the above-mentioned range, theratio of the monovalent metal oxide in the second insulating layer 136 bis increased.

In some other embodiments, a wet process 13 is performed on theconductive structure 114 and transforms an outer part of the insulatinglayer 136 a to a second insulating layer 136 b. The second insulatinglayer 136 b is formed over the conductive structure 114, as shown inFIG. 1H′, in accordance with some embodiments of the disclosure.

In some embodiments, the wet process 13 includes placing the substrate102 in a chemical bath 20. The chemical bath 20 includes an input 202and an output 204. The input 202 is used to provide an input for thechemical solution, and the output 204 is used to provide an output forthe chemical solution. A propeller 206 is used to stir and circulate thechemical solution, and therefore the substrate 102 may be uniformlyreacted with the chemical solution.

After the wet process 13, the insulating layer 136 including the firstinsulating layer 136 a′ and the second insulating layer 136 b isobtained. The first insulating layer 136 a′ includes monovalent metaloxide and the divalent metal oxide. The second insulating layer 136 bincludes monovalent metal oxide and the divalent metal oxide. In someembodiments, the monovalent metal oxide is cuprous oxide (Cu₂O), and thedivalent metal oxide is cupric oxide (CuO) or copper hydroxide(Cu(OH)₂).

It should be noted that a weight ratio of the monovalent metal oxide inthe second insulating layer 136 b is greater than a weight ratio of themonovalent metal oxide in first insulating layer 136 a′. In someembodiments, a ratio of the monovalent metal oxide in the secondinsulating layer 136 b is in a range from about 30 wt % to about 60 wt%. In some embodiments, a ratio of the monovalent metal oxide in thefirst insulating layer 136 a′ is in a range from about 20 wt % to about28 wt %.

In some embodiments, the chemical solution includes hydrogen peroxide(H₂O₂) solution. In some embodiments, the hydrogen peroxide (H₂O₂)solution has a concentration in a range from about 20 wt % to about 60wt %. In some embodiments, the chemical bath 20 is performed at roomtemperature. In some embodiments, the chemical bath 20 is performed at atemperature in a range from about 20 degrees to about 40 degrees.

After the wet process 13, an optional cleaning process is performed onthe insulating layer 136. The cleaning process is used to remove somecontaminations which may come from the chemical bath 20. Ifcontaminations are remaining over the insulating layer 136, thecontaminations may block the adhering of the package layer 140. In someembodiments, the cleaning process includes using nitrogen (N₂) gas witha flow rate in a range from about 200 sccm to about 700 sccm.

It should be noted that the hydrogen peroxide (H₂O₂) solution is easy toprepare and the chemical bath 20 is performed at room temperaturewithout heating the chemical bath 20. Therefore, the cost for performingthe wet process 13 is relatively low. The wet process 13 may be used formass production.

As mentioned above, the adhesion between the conductive structure 114and the package layer 140 is improved by performing the plasma process11 or performing the wet process 13. The delaminated problem is avoided.Therefore, the reliability and performance of the package structure 100are further improved.

Afterwards, the package layer 140 is formed over the semiconductor die120 and the insulating layer 136 as shown in FIG. 1I, in accordance withsome embodiments of the disclosure. In some embodiments, the packagelayer 140 completely encapsulates and covers the semiconductor die 120.The top surface of the package layer 140 is higher than the top surfaceof the conductive structure 114 and the top surface of the semiconductordie 120.

In some embodiments, the package layer 140 is made of molding compound,such as liquid epoxy, deformable gel, silicon rubber, or the like. Insome embodiments, the molding compound is dispensed over the base layer106, the semiconductor die 120 and the insulating layer 136 andtherefore a thermal process is performed to harden the molding compound.

After the package layer 140 is formed, a planarizing process isperformed to expose the semiconductor die 120 and the through InFO vias(TIV) 116, as shown in FIG. J, in accordance with some embodiments ofthe disclosure. After the planarizing process, the top surface of thesemiconductor die 120 is substantially level with that of the conductivestructure 114. In some embodiments, the planarizing process includesgrinding process, a chemical mechanical polishing (CMP) process, anetching process, another applicable process or combinations thereof.

After the planarizing process, a redistribution structure 146 is formedover the package layer 140 as shown in FIG. 1K, in accordance with someembodiments of the disclosure. The redistribution structure 146 includesthe redistribution lines (RDL) 144 formed in the passivation layer 142.The RDL 144 is electrically connected to the semiconductor die 120 andthe through InFO vias (TIV) 116.

In some embodiments, the redistribution lines (RDL) 144 are made ofmetal materials, such as copper (Cu), copper alloy, aluminum (Al),aluminum alloy, tungsten (W), tungsten alloy, titanium (Ti), titaniumalloy, tantalum (Ta), or tantalum alloy. In some embodiments, the RDL144 is formed by plating, electroless plating, sputtering or chemicalvapor deposition (CVD). In some embodiments, the passivation layer 142is made of polybenzoxazole (PBO), benzocyclobutene (BCB), silicone,acrylates, siloxane, or combinations thereof. In some other embodiments,the passivation layer 142 is made of non-organic materials, such assilicon oxide, un-doped silicate glass, silicon oxynitride, solderresist (SR), silicon nitride, HMDS (hexamethyldisilazane).

Afterwards, electrical connector 148 is formed over the redistributionstructure 146. In some embodiments, the electrical connector 148includes the solder ball, metal pillar, another applicable connector. Insome embodiments, an under bump metallurgy (UBM) layer (not shown) isformed below the electrical connector 148.

Afterwards, the substrate 102 and the adhesive layer 104 are removed,and the structure of FIG. 1K is flipped and attached to a carrier 152,as shown in FIG. 1L, in accordance with some embodiments of thedisclosure. As a result, the base layer 106 faces up and is exposed. Thecarrier 152 includes a tape which is photosensitive or heat-sensitiveand is easily detached from the electrical connector 148.

Afterwards, a portion of the base layer 106 is removed to form opening154, as shown in FIG. 1M, in accordance with some embodiments of thedisclosure. In some embodiments, a portion of the seed layer 108 isremoved, and the seed layer 108 is exposed. In some other embodiments,the seed layer 108 is not removed or completely removed. In some otherembodiments, the opening 154 is formed by a laser drilling process, anetching process, or another applicable process.

After the opening 154 is formed, an electrical connector 158 is filledinto the opening 154, as shown in FIG. 1N, in accordance with someembodiments of the disclosure. Afterwards, the top package 160 is bondedto the electrical connector 158. The top package 160 includes a packagesubstrate 162 and semiconductor dies 164. In some embodiments, thesemiconductor dies 164 includes memory dies, such as Static RandomAccess Memory (SRAM) die, Dynamic Random Access Memory (DRAM) die or thelike.

Afterwards, the semiconductor structure 100 may continue to undergoother processes to form other structures or devices. Afterwards, adicing process is performed to separate the structure as shown in FIG.1N, into chip packages.

FIG. 2A shows a top-view representation of a conductive structure 114,before the plasma process 11 or the wet process 13 in accordance withsome embodiments of the disclosure. As shown in FIG. 2A, the firstinsulating layer 136 a surrounds the conductive structure 14, and thetop-view shape of the conductive structure 114 is a circle.

FIG. 2B shows a top-view representation of a conductive structure 114after the plasma process 11 or the wet process 13, in accordance withsome embodiments of the disclosure. After performing the plasma process11 or the wet process 13, the second insulating layer 136 b formed overthe first insulating layer 136 a′ is obtained. The second insulatinglayer 136 b will be in direct contact with the package layer 140. Thesurface roughness of the second insulating layer 136 b is increased toimprove the adhesion between the conductive structure 114 and thepackage layer 140.

As mentioned above, the insulating layer 136 includes monovalent metaloxide at a first location near an outside surface of the insulatinglayer 136 more than it at a second location near an inner surface whichis in contact with the conductive structure 114. The description of“near an outer surface” is in the thickness range of the secondinsulating layer 136 b, and “near an inner surface” is in the thicknessin the first insulating layer 136 a′.

FIG. 3A shows a top-view representation of a conductive structure 114,in accordance with some embodiments of the disclosure. As shown in FIG.3A, a first insulating layer 136 a surrounds the conductive structure114, and the top-view shape of the conductive structure 114 isrectangle.

FIG. 3B shows a top-view representation of a conductive structure 114after the plasma process 11 or the wet process 13, in accordance withsome embodiments of the disclosure. The weight ratio of the monovalentmetal oxide in the second insulating layer 136 b is greater than aweight ratio of the monovalent metal oxide in first insulating layer 136a′. The bonding strength is improved by altering the ratio of the secondinsulating layer 136 b. As a result, the reliability and performance ofthe package structure 100 are further improved.

Embodiments for forming a package structure and method for forming thesame are provided. A semiconductor die is formed over a substrate, and apackage layer covers the semiconductor die. A conductive structure isformed in the package layer, and the insulating layer is formed betweenthe conductive structure and the package layer. A plasma process or awet process is performed on the conductive structure to form theinsulating layer including a first insulating layer and a secondinsulating layer. The second insulating layer is in direct contact withthe package layer and has a larger surface roughness to improve theadhesion. When the adhesion is improved, the delamination problem isavoided. Therefore, the performance of the package structure is alsoimproved.

In some embodiments, a package structure is provided. The packagestructure includes a substrate and a semiconductor die formed over thesubstrate. The package structure also includes a package layer coveringthe semiconductor die and a conductive structure formed in the packagelayer. The package structure includes a first insulating layer formed onthe conductive structure, and the first insulating layer includesmonovalent metal oxide. The package structure includes a secondinsulating layer formed between the first insulating layer and thepackage layer. The second insulating layer includes monovalent metaloxide, and a weight ratio of the monovalent metal oxide in the secondinsulating layer is greater than a weight ratio of the monovalent metaloxide in first insulating layer.

In some embodiments, a package structure is provided. The packagestructure includes a substrate and a semiconductor die formed over thesubstrate. The package structure also includes a package layer adjacentto the semiconductor die and a conductive structure formed in thepackage layer. The package structure further includes an insulatinglayer formed on the conductive structure. The insulating layer includesmonovalent metal oxide at a first location near an outside surface ofthe insulating layer more than it at a second location near an innersurface which is in contact with the conductive structure.

In some embodiments, a method for forming a package structure isprovided. The method includes forming a conductive structure over asubstrate and forming a semiconductor die over a substrate. Thesemiconductor die is surrounded by the conductive structure. The methodfurther includes performing a wet process or a plasma process on theconductive structure to form an insulating layer over the conductivestructure. The insulating layer includes a second insulating layer overa first insulating layer, and the first insulating layer and the secondinsulating layer both include monovalent metal oxide. A weight ratio ofthe monovalent metal oxide in the second insulating layer is greaterthan a weight ratio of the monovalent metal oxide in first insulatinglayer. The method also includes forming a package layer over thesemiconductor die and the second insulating layer.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A package structure, comprising: a substrate; asemiconductor die formed over the substrate; a package layer adjacent tothe semiconductor die; a conductive structure formed in the packagelayer; a first insulating layer formed on the conductive structure,wherein the first insulating layer comprises monovalent metal oxide; anda second insulating layer formed between the first insulating layer andthe package layer, wherein the second insulating layer comprises themonovalent metal oxide, and wherein a weight ratio of the monovalentmetal oxide in the second insulating layer is greater than a weightratio of the monovalent metal oxide in the first insulating layer. 2.The package structure as claimed in claim 1, wherein the conductivestructure comprises a metal material, and the monovalent metal oxidecomprises a metal element that is the same as that of the metalmaterial.
 3. The package structure as claimed in claim 1, wherein thefirst insulating layer further comprises divalent metal oxide, thesecond insulating layer further comprises divalent metal oxide, and aweight ratio of the divalent metal oxide in the second insulating layeris smaller than a weight ratio of the divalent metal oxide in the firstinsulating layer.
 4. The package structure as claimed in claim 3,wherein the monovalent metal oxide is cuprous oxide (Cu₂O), and thedivalent metal oxide is cupric oxide (CuO).
 5. The package structure asclaimed in claim 1, wherein the weight ratio of the monovalent metaloxide in the second insulating layer is in a range from about 30 wt % toabout 60 wt %.
 6. The package structure as claimed in claim 1, wherein asurface roughness of the second insulating layer is greater than asurface roughness of the first insulating layer.
 7. The packagestructure as claimed in claim 1, wherein the second insulating layer isin contact with the package layer.
 8. The package structure as claimedin claim 1, further comprising: a redistribution layer formed over thepackage layer, wherein the redistribution layer is electricallyconnected to the semiconductor die.
 9. The package structure as claimedin claim 1, wherein the first insulating layer is a native oxide layer.10. A package structure, comprising: a substrate; a semiconductor dieformed over the substrate; a package layer adjacent to the semiconductordie; a conductive structure formed in the package layer; and aninsulating layer formed on the conductive structure, wherein theinsulating layer comprises more monovalent metal oxide at a firstlocation near an outside surface of the insulating layer than at asecond location near an inner surface which is in contact with theconductive structure.
 11. The package structure as claimed in claim 10,wherein the conductive structure comprises a metal material, and themonovalent metal oxide comprises a metal element that is the same asthat of the metal material.
 12. The package structure as claimed inclaim 10, wherein a weight ratio of the monovalent metal oxide near theoutside surface of the insulating layer is about 1.5 to about 3 timesgreater than a weight ratio of the monovalent metal oxide near the innersurface of the insulating layer.
 13. The package structure as claimed inclaim 10, further comprising: a redistribution layer formed over thepackage layer, wherein the redistribution layer is electricallyconnected to the semiconductor die.
 14. A package structure comprising:a bottom package comprising: a semiconductor die in a package layer; aconductive structure in the package layer, the conductive structurelaterally spaced from the semiconductor die; a first insulating layer onsidewalls of the conductive structure, the first insulating layercomprising monovalent metal oxide; and a second insulating layer liningthe first insulating layer, the second insulating layer comprising themonovalent metal oxide; wherein a weight ratio of the monovalent metaloxide in the first insulating layer is less than a weight ratio of themonovalent metal oxide in the second insulating layer.
 15. The packagestructure as claimed in claim 14, further comprising a redistributionstructure underlying the package layer.
 16. The package structure asclaimed in claim 15, further comprising a base layer overlying thepackage layer.
 17. The package structure as claimed in claim 16, furthercomprising a top package connected to the bottom package by electricalconnectors formed in the base layer.
 18. The package structure asclaimed in claim 14, wherein the conductive structure is an InFO via(TIV).
 19. The package structure as claimed in claim 14, wherein theconductive structure comprises a metal material, and wherein the firstinsulating layer and the second insulating layer comprise the metalmaterial.
 20. The package structure as claimed in claim 14, wherein asurface roughness of the second insulating layer is greater than asurface roughness of the first insulating layer.